1. Field of the Invention
The present invention relates to a liquid transport apparatus for transporting a liquid, and a method for producing the liquid transport apparatus.
2. Description of the Related Art
An ink-jet head, which jets an ink liquid from nozzles, has been hitherto known as a liquid transport apparatus for transporting the liquid, the ink-jet head including a channel unit which is provided with a plurality of pressure chambers communicated with the nozzles respectively, and a piezoelectric type actuator which selectively applies the pressure to the plurality of pressure chambers.
An ink-jet head described in Japanese Patent Application Laid-open No. 2005-349568 includes a piezoelectric actuator which is arranged on one surface of a channel unit to cover a plurality of pressure chambers therewith. The piezoelectric actuator has a vibration plate which covers the plurality of pressure chambers, a piezoelectric layer which is arranged to cover the plurality of pressure chambers on the surface of the vibration plate disposed on the side opposite to the pressure chambers, a plurality of individual electrodes which are arranged on the piezoelectric layer corresponding to the plurality of pressure chambers respectively, and a common electrode which interposes the piezoelectric layer between the common electrode and the plurality of individual electrodes.
The plurality of individual electrodes are provided on the surface of the vibration plate made of metal with an insulating layer intervening therebetween. The plurality of individual electrodes are in contact with the piezoelectric layer. Wiring sections are led from the plurality of individual electrodes respectively. Each of the wiring sections is laid out, on the surface of the vibration plate (insulating layer), to pass between another individual electrodes which are different from the corresponding individual electrode. The common electrode is provided on the surface, of the piezoelectric layer, not facing the vibration plate to range over the plurality of pressure chambers. The common electrode is always retained at the constant electric potential (ground electric potential). When a predetermined driving voltage is applied via one of the wiring sections to a certain individual electrode among the individual electrodes, the piezoelectric strain arises at the portion, of the piezoelectric layer, interposed by the certain individual electrode and the common electrode. Accordingly, the vibration plate is deformed, the volume of the pressure chamber corresponding to the certain individual electrode is changed, and the pressure is applied to the ink contained in the pressure chamber.
In this arrangement, when the driving electric potential is applied to one of the individual electrodes corresponding to a certain pressure chamber in order to drive the certain pressure chamber (in order to apply the pressure to the ink), the electric potential is necessarily applied simultaneously to the wiring section which is connected to the individual electrode as well. As a result, the electric potential difference is generated between the wiring section and the common electrode, and the piezoelectric strain arises in the piezoelectric layer in an area which is disposed between the another individual electrodes and through which the wiring section is allowed to pass. In this situation, the driving characteristics of another pressure chambers corresponding to the another individual electrodes are changed by being affected by the piezoelectric strain. In view of the above, in the case of the piezoelectric actuator described in Japanese Patent Application Laid-open No. 2005-349568, the areas, of the common electrode, facing the wiring sections are partially cut. Therefore, the electric field is not allowed to act on the piezoelectric layer between the common electrode and the wiring sections.